There are a number of limiting factors that affect the distribution of plant species within a community
- These include temperature, water and light availability, salinity and edaphic factors (soil pH and nutrient levels)
Temperature
- Plants can only survive within a narrow range of temperatures to which they are adapted
- High temperatures will increase the rate of water loss by evaporation and may also denature metabolic enzymes
- Low temperatures may cause plant sap to freeze (the expansion of frozen water in the xylem can cause trunks to split)
- Certain species of woody plants (e.g. maple trees) synthesise antifreeze protein to prevent crystal formation in frozen cells
Water Availability
- Water is needed for photosynthetic processes and is also necessary for maintaining cell turgor
- Xerophytes (e.g. cacti) are plant species that are adapted to survive in dry and arid environments – such as deserts
- Hydrophytes (e.g. rice) are plant species that are adapted to survive in frequently waterlogged soils
Light Availability
- Light is essential to the process of photosynthesis – whereby plants produce organic molecules
- Low-growing plants will typically possess darker green leaves (more chlorophyll) in order to optimise their light conversion
- Certain seaweeds (e.g. kelp) have pigments adapted to absorbing blue wavelengths (red does not easily penetrate water)
Salinity
- Most plants have a low soil salinity tolerance and can only exist within a narrow range of salinity
- High salinity may be toxic to plants and makes the uptake of water via osmosis more difficult
- Halophytes (e.g. mangroves) are plant species that are adapted to tolerate high levels of salinity
Ecological Limiting Factors – Plants
